SIPPING WG R. Mahy
Internet-Draft Cisco Systems, Inc.
Expires: April 1, 2003 Oct 2002
A Message Summary and Message Waiting Indication Event Package for
the Session Initiation Protocol (SIP)
draft-ietf-sipping-mwi-01.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at http://
www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 1, 2003.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This draft proposes a SIP event package to carry message waiting
status and message summaries from a messaging system to an interested
User Agent.
Mahy Expires April 1, 2003 [Page 1]
Internet-Draft SIP Message Waiting Oct 2002
Table of Contents
1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Background and Appropriateness . . . . . . . . . . . . . . . 3
3. Event Package Formal Definition . . . . . . . . . . . . . . 4
3.1 Event Package Name . . . . . . . . . . . . . . . . . . . . . 4
3.2 Event Package Parameters . . . . . . . . . . . . . . . . . . 4
3.3 SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . . 4
3.4 Subscription Duration . . . . . . . . . . . . . . . . . . . 4
3.5 NOTIFY Bodies . . . . . . . . . . . . . . . . . . . . . . . 4
3.6 Subscriber generation of SUBSCRIBE requests . . . . . . . . 6
3.7 Notifier processing of SUBSCRIBE requests . . . . . . . . . 6
3.8 Notifier generation of NOTIFY requests . . . . . . . . . . . 7
3.9 Subscriber processing of NOTIFY requests . . . . . . . . . . 7
3.10 Handling of Forked Requests . . . . . . . . . . . . . . . . 7
3.11 Rate of notifications . . . . . . . . . . . . . . . . . . . 7
3.12 State Agents . . . . . . . . . . . . . . . . . . . . . . . . 8
3.13 Behavior of a Proxy Server . . . . . . . . . . . . . . . . . 8
4. Examples of Usage . . . . . . . . . . . . . . . . . . . . . 8
4.1 Example Message Flow . . . . . . . . . . . . . . . . . . . . 8
4.2 Example Usage with Caller Preferences . . . . . . . . . . . 14
5. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . 14
5.1 New event-package definition . . . . . . . . . . . . . . . . 14
5.2 Body Format Syntax . . . . . . . . . . . . . . . . . . . . . 15
6. Security Considerations . . . . . . . . . . . . . . . . . . 15
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . 15
7.1 SIP Event Package Registration for message-summary . . . . . 16
7.2 MIME Registration for application/simple-message-summary . . 16
8. Revision history . . . . . . . . . . . . . . . . . . . . . . 16
8.1 Open Issues . . . . . . . . . . . . . . . . . . . . . . . . 17
8.2 Changes from draft-ietf-sipping-mwi-00 . . . . . . . . . . . 17
8.3 Changes from draft-mahy-sipping-mwi-00 . . . . . . . . . . . 17
8.4 Changes from draft-mahy-sip-mwi-01 . . . . . . . . . . . . . 18
8.5 Changes from draft-mahy-sip-mwi-00 . . . . . . . . . . . . . 18
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 19
Normative References . . . . . . . . . . . . . . . . . . . . 19
Informational References . . . . . . . . . . . . . . . . . . 19
Author's Address . . . . . . . . . . . . . . . . . . . . . . 20
Full Copyright Statement . . . . . . . . . . . . . . . . . . 21
Mahy Expires April 1, 2003 [Page 2]
Internet-Draft SIP Message Waiting Oct 2002
1. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [3].
2. Background and Appropriateness
Messaging Waiting Indication is a common feature of telephone
networks. It typically involves an audible or visible indication
that messages are waiting, such as playing a special dial tone
(called message-waiting dial tone), lighting a light or indicator on
the phone, displaying icons or text, or some combination. Message-
waiting dial tone is similar but distinct from stutter dial tone.
Both are defined in GR-506 [10].
The methods in the SIP [1] base specification were only designed to
solve the problem of session initiation for multimedia sessions, and
rendezvous. Since Message Waiting Indication is really status
information orthogonal to a session, it was not clear how an IP
telephone acting as a SIP User Agent would implement comparable
functionality. Members of the telephony community viewed this as a
shortcoming of SIP.
Users want the useful parts of the functionality they have using
traditional analog, mobile, and PBX telephones. It is also desirable
to provide comparable functionality in a flexible way that allows for
more customization and new features.
SIP Specific Event Notification (RFC 3265 -- SIP Events) [2] is an
appropriate mechanism to use in this environment, as it preserves the
user mobility and rendezvous features which SIP provides.
Using SIP-Specific Event Notification, A Subscriber User Agent
(typically an IP phone or SIP software User Agent) subscribes to the
status of their messages. A SIP User Agent acting on behalf of the
user's messaging system then notifies the Subscriber whenever the
messaging account's messages have changed. The Notifier sends this
message summary information in the body of the NOTIFY, encoded in a
new MIME type defined later in this draft. A User Agent can also
explicitly fetch the current status.
A SIP User Agent MAY subscribe to multiple accounts (distinguished by
the Request URI). Multiple SIP User Agents MAY subscribe to the same
account.
Before any subscriptions or notifications are sent, each interested
User Agent must be made aware of its messaging server(s). This MAY
Mahy Expires April 1, 2003 [Page 3]
Internet-Draft SIP Message Waiting Oct 2002
be manually configured on interested User Agents, manually configured
on an appropriate SIP Proxy, or dynamically discovered using caller
preferences [4]. (For more information on usage with caller
preferences, see Section 4.2)
3. Event Package Formal Definition
3.1 Event Package Name
This document defines a SIP Event Package as defined in RFC 3265 [2].
The event-package token name for this package is:
"message-summary"
3.2 Event Package Parameters
This package does not define any event package parameters.
3.3 SUBSCRIBE Bodies
This package does not define any SUBSCRIBE bodies.
3.4 Subscription Duration
Subscriptions to this event package MAY range from minutes to weeks.
Subscriptions in hours or days are more typical and are RECOMMENDED.
3.5 NOTIFY Bodies
A simple text-based format is proposed to prevent an undue burden on
low-end user agents, for example, inexpensive IP phones with no
display. Although this format is text-based, it is intended for
machine consumption only.
A future extension MAY define other NOTIFY bodies. If no "Accept"
header is present in the SUBSCRIBE, the body type defined in this
document MUST be assumed.
The format specified in this proposal attempts to separate orthogonal
attributes of messages as much as possible. Messages are separated
by message-context-class (for example: voice-message, fax-message,
pager-message, multimedia-message, text-message, and none); by
message status (new and old); and by urgent and non-urgent type.
The text format begins with a simple status line, and optionally a
summary line per message-context-class. Message-context-classes are
defined in [6]. For each message-context-class, the total number of
Mahy Expires April 1, 2003 [Page 4]
Internet-Draft SIP Message Waiting Oct 2002
new and old messages is reported in the new and old fields.
In some cases, detailed message summaries are not available. The
status line allows messaging systems or messaging gateways to provide
the traditional boolean message waiting notification.
Messages-Waiting: yes
If the Request-URI or To header in a message-summary subscription
corresponds to a group or collection of individual messaging
accounts, the notifier MUST specify to which account the message-
summary body corresponds. Note that the account URI MUST NOT be
delimited with angle brackets ("<" and ">").
Message-Account: sip:alice@example.com
In the example that follows, more than boolean message summary
information is available to the User Agent. There are two new and
four old fax messages.
Fax-Message: 2/4
After the summary, the format can optionally list a summary count of
urgent messages. In the next example there are one new and three old
voice messages, none of the new messages are urgent, but one of the
old messages is. All counters have a maximum value of 4,294,967,295
((2^32) - 1). Notifiers MUST NOT generate a request with a larger
value. Subscribers MUST treat a larger value as 2^32-1.
Voice-Message: 1/3 (0/1)
Optionally, after the summary counts, the messaging systems MAY
append RFC 2822 [9]-style message headers, which further describe
newly added messages. Message headers MUST NOT be included in an
initial NOTIFY, as new messages could be essentially unbounded in
size. Message headers included in subsequent notifications MUST only
correspond to messages added since the previous notification for that
subscription. A messaging system which includes message headers in a
NOTIFY, MUST provide an administrator configurable mechanism for
selecting which headers are sent. Likely headers for inclusion
include To, From, Date, Subject, and Message-ID. Note that the
formatting of these headers is identical to that of SIP extension-
headers, not the (similar) format defined in RFC 2822.
Implementations which generate large notifications are reminded to
follow the message size restrictions for unreliable transports
articulated in Section 18.1.1 of SIP.
Mahy Expires April 1, 2003 [Page 5]
Internet-Draft SIP Message Waiting Oct 2002
Mapping local message state to new/old message status and urgency is
an implementation issue of the messaging system. However, the
messaging system MUST NOT consider a message "old" merely because it
generated a notification , as this could prevent another subscription
from accurately receiving message-summary notifications. Likewise,
the messaging system MAY use any suitable algorithm to determine that
a message is "urgent".
Messaging systems MAY use any algorithm for determining the
approporiate message-context-class for a specific message. Systems
which use Internet Mail SHOULD use the contents of the Message-
Context header [6] if present as a hint to make a context
determination. Note that a messaging system does not need to support
a given context in order to generate notifications identified with
that context.
3.6 Subscriber generation of SUBSCRIBE requests
Subscriber User Agents will typically SUBSCRIBE to message summary
information for a period of hours or days, and automatically attempt
to re-SUBSCRIBE well before the subscription is completely expired.
If re-subscription fails, the Subscriber SHOULD periodically retry
again until a subscription is successful, taking care to backoff to
avoid network congestion. If a subscription has expired, new re-
subscriptions MUST use a new Call-ID.
The Subscriber SHOULD SUBSCRIBE to that user's message summaries
whenever a new user becomes associated with the device (a new login).
The Subscriber MAY also explicitly fetch the current status at any
time. The subscriber SHOULD renew its subscription immediately after
a reboot, or when the subscriber's network connectivity has just been
re-established.
The Subscriber MUST be prepared to receive and process a NOTIFY with
new state immediately after sending a new SUBSCRIBE, a SUBSCRIBE,
renewal, an unSUBSCRIBE or a fetch; or at any time during the
subscription.
When a user de-registers from a device (logoff, power down of a
mobile device, etc.), subscribers SHOULD unsubscribe by sending a
SUBSCRIBE message with an Expires header of zero.
3.7 Notifier processing of SUBSCRIBE requests
When a SIP Messaging System receives SUBSCRIBE messages with the
message-summary event-type, it SHOULD authenticate the subscription
request. If authentication is successful, the Notifier MAY limit the
duration of the subscription to an administrator defined amount of
Mahy Expires April 1, 2003 [Page 6]
Internet-Draft SIP Message Waiting Oct 2002
time as described in SIP Events.
3.8 Notifier generation of NOTIFY requests
Immediately after a subscription is accepted, the Notifier MUST send
a NOTIFY with the current message summary information. This allows
the Subscriber to resynchronize its state. This initial
synchronization NOTIFY MUST NOT include the optional message headers.
When the status of the messages changes sufficiently for a messaging
account to change the number of new or old messages, the Notifier
SHOULD send a NOTIFY message to all active subscribers to that
account. NOTIFY messages sent to subscribers of a group or alias,
MUST contain the message account name in the notification body.
A Messaging System MAY send a NOTIFY with an "Expires" header of "0"
and a "Subscription-State" header of "terminated" before a graceful
shutdown.
3.9 Subscriber processing of NOTIFY requests
Upon receipt of a valid NOTIFY request, the subscriber SHOULD
immediately render the message status and summary information to the
end user in an implementation specific way.
The Subscriber MUST be prepared to receive NOTIFYs from different
Contacts corresponding to the same SUBSCRIBE. (the SUBSCRIBE may
have been forked).
3.10 Handling of Forked Requests
Forked requests are allowed for this event type and may install
multiple subscriptions. The Subscriber MAY render multiple summaries
which correspond to the same account directly to the user, or MAY
merge them as described below.
If any of the "Messages-Waiting" status lines report "yes", then the
merged state is "yes"; otherwise the merged state is "no".
The Subscriber MAY merge summary lines in an implementation-specific
way if all notifications contain at least one msg-summary line.
3.11 Rate of notifications
A Notifier MAY choose to hold NOTIFY requests in "quarantine" for a
short administrator-defined period (seconds or minutes) when the
message status is changing rapidly. Requests in the quarantine which
become invalid are replaced by newer notifications, thus reducing the
Mahy Expires April 1, 2003 [Page 7]
Internet-Draft SIP Message Waiting Oct 2002
total volume of notifications. This behavior is encouraged for
implementations with heavy interactive use. Note that timely
notification which results in a change of overall state (messages
waiting or not), and notification of newly added messages is probably
more significant to the end user than a notification of newly deleted
messages which do not affect the overall message waiting state (e.g.
there are still new messages).
Notifiers SHOULD NOT generate NOTIFY requests more frequently than
once per second.
3.12 State Agents
A Subscriber MAY use an "alias" or "group" in the Request-URI of a
subscription if that name is significant to the messaging system.
Implementers MAY create a service which consolidates and summarizes
NOTIFYs from many Contacts. This document does not preclude
implementations from building state agents which support this event
package.
3.13 Behavior of a Proxy Server
There are no additional requirements on a SIP Proxy, other than to
transparently forward the SUBSCRIBE and NOTIFY methods as required in
SIP. However, Proxies SHOULD allow non-SIP URLs. Proxies and
Redirect servers SHOULD be able to direct the SUBSCRIBE request to an
appropriate messaging server User Agent. Proxies are encouraged to
support routing to Contacts based on the the method of the request
and the existence of a feature="voice-mail" parameter in an Accept-
Contact header (as specified in the caller preferences
specification).
4. Examples of Usage
4.1 Example Message Flow
The examples shown below are for informational purposes only. For a
normative description of the event package, please see sections 3 and
5 of this document.
In the example call flow below, Alice's IP phone subscribes to the
status of Alice's messages. Via headers are omitted for clarity.
Subscriber Notifier
| |
| A1: SUBSCRIBE (new) |
|---------------------->|
| A2: 200 OK |
Mahy Expires April 1, 2003 [Page 8]
Internet-Draft SIP Message Waiting Oct 2002
|<----------------------|
| |
| A3: NOTIFY (sync) |
|<----------------------|
| A4: 200 OK |
|---------------------->|
| |
| |
| A5: NOTIFY (change) |
|<----------------------|
| A6: 200 OK |
|---------------------->|
| |
| |
| A7: (re)SUBSCRIBE |
|---------------------->|
| A8: 200 OK |
|<----------------------|
| |
| A9: NOTIFY (sync) |
|<----------------------|
| A10: 200 OK |
|---------------------->|
| |
| |
| A11: (un)SUBSCRIBE |
|---------------------->|
| A12: 200 OK |
|<----------------------|
| |
| A13: NOTIFY (sync) |
|<----------------------|
| A14: 200 OK |
|---------------------->|
A1: Subscriber (Alice's phone) ->
Notifier (Alice's voicemail gateway)
Subscribe to Alice's message summary status for 1 day.
SUBSCRIBE sip:alice@vmail.example.com SIP/2.0
To: <sip:alice@example.com>
From: <sip:alice@example.com>;tag=78923
Date: Mon, 10 Jul 2000 03:55:06 GMT
Call-Id: 1349882@alice-phone.example.com
CSeq: 4 SUBSCRIBE
Contact: <sip:alice@alice-phone.example.com>
Event: message-summary
Mahy Expires April 1, 2003 [Page 9]
Internet-Draft SIP Message Waiting Oct 2002
Expires: 86400
Accept: application/simple-message-summary
Content-Length: 0
A2: Notifier -> Subscriber
SIP/2.0 200 OK
To: <sip:alice@example.com>;tag=4442
From: <sip:alice@example.com>;tag=78923
Date: Mon, 10 Jul 2000 03:55:07 GMT
Call-Id: 1349882@alice-phone.example.com
CSeq: 4 SUBSCRIBE
Expires: 86400
Content-Length: 0
A3: Notifier -> Subscriber
(immediate synchronization of current state:
2 new and 8 old [2 urgent] messages)
NOTIFY sip:alice@alice-phone.example.com SIP/2.0
To: <sip:alice@example.com>;tag=78923
From: <sip:alice@example.com>;tag=4442
Date: Mon, 10 Jul 2000 03:55:07 GMT
Call-Id: 1349882@alice-phone.example.com
CSeq: 20 NOTIFY
Contact: <sip:alice@vmail.example.com>
Event: message-summary
Subscription-State: active
Content-Type: application/simple-message-summary
Content-Length: 99
Messages-Waiting: yes
Message-Account: sip:alice@vmail.example.com
Voice-Message: 2/8 (0/2)
A4: Subscriber -> Notifier
SIP/2.0 200 OK
To: <sip:alice@example.com>;tag=78923
From: <sip:alice@example.com>;tag=4442
Date: Mon, 10 Jul 2000 03:55:08 GMT
Call-Id: 1349882@alice-phone.example.com
CSeq: 20 NOTIFY
Content-Length: 0
A5: Notifier -> Subscriber
This is a notification of new messages.
Some headers from each of the new messages are appended.
Mahy Expires April 1, 2003 [Page 10]
Internet-Draft SIP Message Waiting Oct 2002
NOTIFY sip:alice@alice-phone.example.com SIP/2.0
To: <sip:alice@example.com>;tag=78923
From: <sip:alice@example.com>;tag=4442
Date: Mon, 10 Jul 2000 04:28:53 GMT
Contact: <sip:alice@vmail.example.com>
Call-ID: 1349882@alice-phone.example.com
CSeq: 31 NOTIFY
Event: message-summary
Subscription-State: active
Content-Type: application/simple-message-summary
Content-Length: 503
Messages-Waiting: yes
Message-Account: sip:alice@vmail.example.com
Voice-Message: 4/8 (1/2)
To: <alice@atlanta.com>
From: <bob@biloxi.com>
Subject: carpool tomorrow?
Date: Sun, 09 Jul 2000 21:23:01 -0700
Priority: normal
Message-ID: 13784434989@vmail.example.com
To: <alice@example.com>
From: <cathy-the-bob@example.com>
Subject: HELP! at home ill, present for me please
Date: Sun, 09 Jul 2000 21:25:12 -0700
Priority: urgent
Message-ID: 13684434990@vmail.example.com
A6: Subscriber -> Notifier
SIP/2.0 200 OK
To: <sip:alice@example.com>;tag=78923
From: <sip:alice@example.com>;tag=4442
Date: Mon, 10 Jul 2000 04:28:53 GMT
Call-ID: 1349882@alice-phone.example.com
CSeq: 31 NOTIFY
Content-Length: 0
A7: Subscriber -> Notifier
Refresh subscription.
SUBSCRIBE sip:alice@vmail.example.com SIP/2.0
To: <sip:alice@example.com>;tag=4442
From: <sip:alice@example.com>;tag=78923
Date: Mon, 10 Jul 2000 15:55:06 GMT
Call-Id: 1349882@alice-phone.example.com
Mahy Expires April 1, 2003 [Page 11]
Internet-Draft SIP Message Waiting Oct 2002
CSeq: 8 SUBSCRIBE
Contact: <sip:alice@alice-phone.example.com>
Event: message-summary
Expires: 86400
Accept: application/simple-message-summary
Content-Length: 0
A8: Notifier -> Subscriber
SIP/2.0 200 OK
To: <sip:alice@example.com>;tag=4442
From: <sip:alice@example.com>;tag=78923
Date: Mon, 10 Jul 2000 15:55:07 GMT
Call-Id: 1349882@alice-phone.example.com
CSeq: 8 SUBSCRIBE
Contact: <sip:alice@alice-phone.example.com>
Expires: 86400
Content-Length: 0
A9: Notifier -> Subscriber
(immediate synchronization of current state)
NOTIFY sip:alice@alice-phone.example.com SIP/2.0
To: <sip:alice@example.com>;tag=78923
From: <sip:alice@example.com>;tag=4442
Date: Mon, 10 Jul 2000 15:55:07 GMT
Call-Id: 1349882@alice-phone.example.com
CSeq: 47 NOTIFY
Contact: <sip:alice@vmail.example.com>
Event: message-summary
Subscription-State: active
Content-Type: application/simple-message-summary
Content-Length: 99
Messages-Waiting: yes
Message-Account: sip:alice@vmail.example.com
Voice-Message: 4/8 (1/2)
A10: Subscriber -> Notifier
SIP/2.0 200 OK
To: <sip:alice@example.com>;tag=78923
From: <sip:alice@example.com>;tag=4442
Date: Mon, 10 Jul 2000 15:55:08 GMT
Call-Id: 1349882@alice-phone.example.com
CSeq: 47 NOTIFY
Contact: <sip:alice@vmail.example.com>
Mahy Expires April 1, 2003 [Page 12]
Internet-Draft SIP Message Waiting Oct 2002
A11: Subscriber -> Notifier
Un-subscribe after "alice" logs out.
SUBSCRIBE sip:alice@vmail.example.com SIP/2.0
To: <sip:alice@example.com>;tag=4442
From: <sip:alice@example.com>;tag=78923
Date: Mon, 10 Jul 2000 19:35:06 GMT
Call-Id: 1349882@alice-phone.example.com
CSeq: 17 SUBSCRIBE
Contact: <sip:alice@alice-phone.example.com>
Event: message-summary
Expires: 0
Accept: application/simple-message-summary
Content-Length: 0
A12: Notifier -> Subscriber
SIP/2.0 200 OK
To: <sip:alice@example.com>;tag=4442
From: <sip:alice@example.com>;tag=78923
Date: Mon, 10 Jul 2000 19:35:07 GMT
Call-Id: 1349882@alice-phone.example.com
CSeq: 17 SUBSCRIBE
Contact: <sip:alice@alice-phone.example.com>
Expires: 0
Content-Length: 0
A13: Notifier -> Subscriber
(immediate synchronization of current state,
which the subscriber can now ignore)
NOTIFY sip:alice@alice-phone.example.com SIP/2.0
To: <sip:alice@example.com>;tag=78923
From: <sip:alice@example.com>;tag=4442
Date: Mon, 10 Jul 2000 19:35:07 GMT
Call-Id: 1349882@alice-phone.example.com
CSeq: 56 NOTIFY
Contact: <sip:alice@vmail.example.com>
Event: message-summary
Subscription-State: terminated;reason=timeout
Content-Type: application/simple-message-summary
Content-Length: 99
Messages-Waiting: yes
Message-Account: sip:alice@vmail.example.com
Voice-Message: 4/8 (1/2)
A10: Subscriber -> Notifier
Mahy Expires April 1, 2003 [Page 13]
Internet-Draft SIP Message Waiting Oct 2002
SIP/2.0 200 OK
To: <sip:alice@example.com>;tag=78923
From: <sip:alice@example.com>;tag=4442
Date: Mon, 10 Jul 2000 19:35:08 GMT
Call-Id: 1349882@alice-phone.example.com
CSeq: 56 NOTIFY
Event: message-summary
Content-Length: 0
4.2 Example Usage with Caller Preferences
The use of caller preferences is optional but encouraged. If caller
preferences is used, a messaging server MAY REGISTER a Contact with
an appropriate methods and events tag as shown in the example below.
To further distinguish itself, the messaging server MAY also REGISTER
as a Contact with the feature="voice-mail" tag. An example of this
kind of registration follows below.
REGISTER sip:sip3-sj.example.com SIP/2.0
To: <sip:alice@example.com>
From: <sip:alice@example.com>;tag=4442
...
Contact: <sip:alice@vm13-sj.example.com>
;feature="voice-mail";methods="SUBSCRIBE"
;events="message-summary"
The following SUBSCRIBE message would find the Contact which
registered in the example above.
SUSBCRIBE sip:alice@example.com SIP/2.0
...
Accept: application/simple-message-summary
Event: message-summary
Accept-Contact: *;feature="voice-mail"
5. Formal Syntax
The following syntax specification uses the augmented Backus-Naur
Form (BNF) as described in RFC-2234 [5].
5.1 New event-package definition
This document defines a new event-package with the package name:
message-summary
Mahy Expires April 1, 2003 [Page 14]
Internet-Draft SIP Message Waiting Oct 2002
5.2 Body Format Syntax
The formal syntax for application/simple-message-summary is below:
messsage-summary = msg-status-line CRLF
[msg-account CRLF]
[*(msg-summary-line CRLF)]
[ *opt-msg-headers ]
msg-status-line = "Messages-Waiting" HCOLON msg-status
msg-status = "yes" / "no"
msg-account = "Message-Account" HCOLON Account-URI
Account-URI = SIP-URI / SIPS-URI / absoluteURI
msg-summary-line = message-context-class HCOLON newmsgs SLASH oldmsgs
[ LPAREN new-urgentmsgs SLASH old-urgentmsgs RPAREN ]
opt-msg-headers = CRLF 1*(extension-header CRLF)
newmsgs = msgcount
oldmsgs = msgcount
new-urgentmsgs = msgcount
old-urgentmsgs = msgcount
msgcount = 1*DIGIT ; MUST NOT exceed 2^32-1
6. Security Considerations
Message Summaries and optional message bodies contain information
which is typically very privacy sensitive. At minimum, subscriptions
to this event package SHOULD be authenticated and properly
authorized. Furthermore, notifications SHOULD be encrypted and
integrity protected using either end-to-end mechanisms, or the hop-
by-hop protection afforded messages sent to SIPS URIs.
Additional security considerations are covered in SIP [1] and SIP
Events [2].
7. IANA Considerations
Mahy Expires April 1, 2003 [Page 15]
Internet-Draft SIP Message Waiting Oct 2002
7.1 SIP Event Package Registration for message-summary
Package name: message-summary
Type: package
Contact: [Mahy]
Published Specification: This document.
7.2 MIME Registration for application/simple-message-summary
MIME media type name: application
MIME subtype name: simple-message-summary
Required parameters: none.
Optional parameters: none.
Encoding considerations: This type is only defined for transfer
via SIP [1].
Security considerations: See the "Security Considerations"
section in this document.
Interoperability considerations: none
Published specification: This document.
Applications which use this media: The simple-message-summary
application subtype supports the exchange of message waiting and
message summary information in SIP networks.
Additional information:
1. Magic number(s): N/A
2. File extension(s): N/A
3. Macintosh file type code: N/A
8. Revision history
Mahy Expires April 1, 2003 [Page 16]
Internet-Draft SIP Message Waiting Oct 2002
8.1 Open Issues
1. Need to update the caller-preference section to reflect whatever
the replacement will be for feature="voice-mail".
2. Would be nice to add a pointer to the "collections" work
8.2 Changes from draft-ietf-sipping-mwi-00
1. Replaced the "media types" concept with message contexts. This
is a better semantic match than what was in the draft before, and
also controls extensibility and change control in a single
document. The list of valid message-context-classes are voice-
message, fax-message, pager-message, multimedia-message, text-
message, and none.
2. Completely updated the syntax to follow that of SIP instead of
the previously more restrictive (and somewhat arbitrary) syntax.
The SIP syntax adds line folding, for example. The optional
message-headers borrow the "extension-header" syntax and explicit
whitespace separators defined in SIP (ex: HCOLON, SLASH).
3. Added a Message-Account field in the body format to provide the
specific account name which corresponds to the notification when
forking or state agents are used with group aliases (or
collections).
4. Changed caller preferences example to exclude methods="SUBSCRIBE"
in the SUBSCRIBE request (removed redundant information).
5. Changed examples to be consistent with IESG recommendations
8.3 Changes from draft-mahy-sipping-mwi-00
1. Updated references and split into normative and informational
2. Removed normative behavior now specified in Events
3. Updated to address the event package sections now specified in
Events.
4. Added the Subscription-State header field to the examples and
removed the Event header field from responses.
5. Removed redundant BNF
Mahy Expires April 1, 2003 [Page 17]
Internet-Draft SIP Message Waiting Oct 2002
6. Simplified text on how to choose the media type. For Internet
Mail, this now references the Message-Context header.
8.4 Changes from draft-mahy-sip-mwi-01
1. This document is now formatted as a SIP Event Package as defined
in Section 4 of RFC 3265 (SIP Events) [2].
2. The event-package name is now "message-summary", to allow for
other bodies to extend the package.
3. The "urgent" token was missing from the BNF.
8.5 Changes from draft-mahy-sip-mwi-00
This draft greatly simplifies and shortens the -00 version.
1. The generic behavior of SUBSCRIBE/NOTIFY is now greatly clarified
in SIP Events [2] and made consistent with PINT and SIP for
presence. This message waiting draft is now consistent with SIP
Events.
2. The XML format has been removed due to lack of immediate
interest. At a future date, similar functionality may be added
as another body definition with an appropriate MIME type.
3. An IANA Considerations section was added to register the new
"application/simple-message-summary" MIME type and the "simple-
message-summary" SIP event package.
4. The "flag-list" was removed due to lack of interest and to
encourage simplicity.
5. Due to synchronization issues, and the recommendation of the VPIM
Working Group, support for message count "deltas" was removed.
6. The Messages-Waiting line in the body is now mandatory.
7. This version of the draft clarifies the role of caller
preferences as optional but encouraged.
8. A set of SMTP-like headers from the triggering messages may now
optionally follow the message summaries, provided that the
resulting NOTIFY on UDP fits in a single datagram.
Mahy Expires April 1, 2003 [Page 18]
Internet-Draft SIP Message Waiting Oct 2002
9. Contributors
Ilya Slain came up with the initial format of the text body contained
in this document. He was previously listed as a co-author, however,
he is no longer reachable.
10. Acknowledgments
Thanks to Dan Wing, Dave Oran, Bill Foster, Steve Levy, Denise
Caballero-McCann, Jeff Michel, Priti Patil, Satyender Khatter, Bich
Nguyen, Manoj Bhatia, David Williams, and Bryan Byerly of Cisco; and
Jonathan Rosenberg and Adam Roach of Dynamicsoft.
Normative References
[1] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
[2] Roach, A., "Session Initiation Protocol (SIP)-Specific Event
Notification", RFC 3265, June 2002.
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[4] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol
(SIP) Caller Preferences and Callee Capabilities", draft-ietf-
sip-callerprefs-06 (work in progress), July 2002.
[5] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[6] Klyne, G., Burger, E., Candell, E. and C. Eliot, "Message
Context for Internet Mail", draft-ietf-vpim-hint-08 (work in
progress), June 2002.
Informational References
[7] Vaudreuil, G. and G. Parsons, "Voice Profile for Internet Mail
- version 2", RFC 2421, September 1998.
[8] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046, November
1996.
[9] Resnick, P., "Internet Message Format", RFC 2822, April 2001.
[10] Telcordia, "GR-506: Signaling for Analog Interfaces, Issue 1,
Mahy Expires April 1, 2003 [Page 19]
Internet-Draft SIP Message Waiting Oct 2002
Revision 1", Nov 1996.
Author's Address
Rohan Mahy
Cisco Systems, Inc.
101 Cooper Street
Santa Cruz, CA 95060
USA
EMail: rohan@cisco.com
Mahy Expires April 1, 2003 [Page 20]
Internet-Draft SIP Message Waiting Oct 2002
Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Mahy Expires April 1, 2003 [Page 21]
